Small park? Square? Small public garden?

[Barb_D]

I'm not much of a city girl, but my brother lives in Toronto, and just down the street is a little park with some playground equipment, benches, grass, and paved paths, and the entire place is probably 1/3 the size you describe. I'd call it a park along with the others here. A park is defined more by what you do there than its size, I think.

[SoothingDave]

I would have no problem with "park," either. And don't know why BobSmith thinks 100 meters long is too big to be a park. Perhaps he is thinking of a parking spot. Most of us Americans could fit our SUVs easily into something that size.

I would also like to suggest the word "commons."